SCREENING OF LACTIC ACID BACTERIAL AND FUNGAL STRAINS FOR THEIR EFFICIENCY IN BIOCONTROL OF MYCOTOXIGENIC CONTAMINANTS OF FOOD PUBLISHEDGabi-Mirela MATEI(1), A.MATEI(2), S.MATEI(1) (1)National RD Institute for Soil Science, Agrochemistry and Environment (2)UASVMB, Faculty of Biotechnologies, Bucharest, Romania Bd. Marasti 61, Sect.1, cod 011464, Bucharest, Romania E-mail: firstname.lastname@example.org
Abstract: The goal of the present paper was to present the results of the research carried out for selecting the most efficient bacterial or fungal strains against certain mycotoxigenic contaminants of vegetal food products in order to use them as biological control agents. Generally, the presence of moulds in foods is associated with decay, spoilage and in certain cases with poisoning, due to dangerous fungal metabolites well-known as mycotoxins. In agriculture, the mycotoxin problem is results of a series of events started from the field, due to fungal infestation of a host plant during the vegetation cycle and the effect are found at the end of the chain, in food and feed. Inappropriate preservation of food during storage can lead to mycotoxin contamination with severe effects on human health. After discovering in 1960 the aflatoxins, carcinogenic metabolites of Aspergillus flavus, research showed that a large number of fungal species could form mycotoxins (e.g. a variety of Fusarium species can release mycotoxins of the class trichotecenes, zearalenone and fumosins). For the screening purpose, a series of lactic acid bacteria selected from fresh or fermented vegetables such as cucumbers, cabbages, from cereals, as well as fungal isolates from cereals, fruits and rhizosphere were tested for their antagonistic effect on the mycotoxigenic fungal species belonging to genera Fusarium, Aspergillus and Penicillium, contaminants of fresh and preserved fruits, vegetables or cereals. Adapted dual culture technique was employed for testing the antagonism between lactic acid bacteria and mycotoxigenic fungi on MRS agar medium and between non-mycotoxigenic and mycotoxigenic fungi on Czapek agar medium. Bacterial and fungal extracts from liquid culture media were used on paper disks method to assess the inhibitory effect on the growth of Fusarium mycotoxigenic species. The paper presents original photographs of the Petri dishes with visible inhibition zones around bacterial extracts from lactic acid bacteria, pseudomonads, as well as from fungi belonging to genus Trichoderma when interacted with mycotoxigenic species of Fusarium. Lactic acid bacteria, Pseudomonas fluorescens, Trichoderma spp. and Myrothecium verrucaria showed important antagonistic effect against mycotoxigenic Aspergillia and Fusaria. They can also be useful for including in biotechnological methods of food preservation.
Key words: antagonistic effect, fungi, inhibition zone, lactic acid bacteria, mycotoxins.